My 2000 5.3 came bone stock with iridium plugs. I know this because at 30,000 miles I yanked mine out to replace them with denso iridium plugs only to find that I already had them! Iridium plugs are a 100,000 mile plug. Don`t believe me? Research it yourself. Platinum plugs are considered a 50,000 mile plug. I`m saying all this to say if you have iridium plugs as OEM (and you probably do), and you aren`t close to 100,000 miles, save your money! I did compliment the plugs with a set of MSD wires though. However, this is only my perspective; do what you want. I`m out!

Factory says to change them at 100k, mine didnt even show wear then but did them anyway. Agree with all the above, go back to stock with at least the plugs, the stock delco wires arnt bad either. Summit has nice prices on both.

agreed, i use ac/delco platinum plugs. i would use iridium but i had heard conflicting reports with my model truck (`9 so i decided to leave them the way they came. i imagine your model came with iridium......

I replaced my for the first time last summer. Stock plugs and wires.
Had 80k+. Sure it would have went longer but my truck ran noticably better. Much snappier feel and I regained nearly 2 mpg. I`ll never even consider pushing plugs to their max again.